This is a 371 of PCT/JP98/05191 filed Nov. 18, 1998.
This invention relates to modified heparins and an agent for remedying skin ulcer. More particularly, this invention relates to using as an agent for remedying skin ulcer modified heparins, especially low molecular weight modified heparins which have been substantially deprived of the anticoagulant activity yet retain the ability to bind to cell growth factors, cytokines and cell adhesion molecules, and also relates to modified heparins, especially low molecular weight modified heparins adapted for use in preparing an agent for remedying skin ulcer.
Heparin is one of glycosaminoglycans and is characterized by having anticoagulant activity. A lot of heparin has been found in liver, lung, intestine, spleen and other organs of healthy edible animals, and heparin is largely produced by mast cells around capillary vessels. A heparin is glycosaminoglycan including various amounts of O-sulfate, N-sulfate and N-acetyl groups and belongs to a heteropolysaccharide having a molecular weight of 6,000xcx9c20,000.
More particularly, heparin is formed by a combination of ten kinds of disaccharide having chemical formulas shown in the following Table 1. 
In the Table, GlcA denotes D-glucuronic acid, GlcNAc N-acetyl-D-glucosamine, GlcNS N-sulfo-D-glucosamine, GIcA (20S) 2-sulfo-D-glucuronic acid, GlcNS(60S) N-sulfo-D-glucsamine-6-sulfate, GlcNS(3,6diOS) N-sulfo-D-glucosamine-3,6-disulfates, IdA L-iduronic acid, IdA(20S) 2-sulfo-L-iduronic acid, respectively.
Heparin exhibits a variety of biological activities. Namely, heparin binds to a wide variety of cell growth factors, cytokines and cell adhesion molecules. The major function of heparin is that it binds to enzymes and factors such as antithrombin HI involved in blood coagulation and fibrinolysis, thus inhibiting blood coagulation as mentioned above.
It has never been anticipated that heparin itself is effective in remedying skin ulcer. It is because, when heparin is applied on the skin ulcer, it would promote hemorrhage due to its inherent anticoagulant property, and accordingly it would be liable to worsen conditions of the skin ulcer.
Some trials have been made to make use of heparin as a drug by depolymerizing heparin to form low molecular weight heparin or by chemically modifying heparin. For example, JP30277/1979 discloses that heparin can be used as an agent for remedying thrombosis when heparin is depolymerized to form low molecular weight heparin having molecular weights of 2,000xcx9c5,000, and the resultant product is then chemically modified.
WO80/01383 discloses that a low molecular weight heparin having a selective anticoagulant activity can be obtained which has a weakened anti-thrombotic activity and a strengthened anti-factor Xa activity, when heparin is treated with nitrite, or oxidized with periodate, and the resultant product is subjected to xcex2-elimination reaction with alkali.
JP66192/1988 discloses that heparin-typed oligosaccharides having an affinity to cell growth factors and showing specific nuclear magnetic resonance spectra can be used for remedying muscle and blood vessel diseases.
WO88/06840 discloses that heparin can be used for preserving and restoring cells when heparin is kept in an appropriate concentration.
U.S. Pat. No. 5,280,016 discloses that a heparin derivative obtained by oxidizing heparin with periodate without depolymerizing heparin and then by reducing the oxidized heparin with borohydride can be used as a drug for injection for inhibiting proliferation of muscle cells.
U.S. Pat. No. 5,296,471 discloses that a heparin derivative obtained by removing 2-O-sulfate and/or 3-O-sulfate groups from heparin to various degrees can be used for preventing and remedying various deseases such as cancer.
JP505179/1995 discloses that when heparin is depolymerized chemically or enzymatically to form various oligosaccharides, which are then divided into various fractions according to properties binding to cell growth factors, thus divided fractions can be used for an agent for adjusting growth of specific cells.
WO96/29973 discloses that, when heparin is depolymerized with nitrite to form low molecular weight heparin, which is then oxidized with periodate, and thereafter the resultant product is further reduced with borohydride, a low molecular weight modified heparin can be obtained which has no anticoagulant activity, and the said modified heparin can be used as a drug for injection for preventing thrombus formation.
WO98/14481 discloses that, when heparin is depolymerized with nitrite to form low molecular weight heparin, which is then oxidized with periodate, and thereafter the resultant product is further reduced with borohydride, a low molecular weight modified heparin can be obtained which has no anticoagulant activity, and the said modified heparin can be used for remedying diseases such as kidney malfunction and myocardial infarction.
As mentioned above, it is known that heparin is depolymerized to form a low molecular weight heparin, the low molecular heparin or heparin itself is chemically modified to form modified derivatives, and the modified derivatives are used for a drug. However, the drug is mainly for use in injection, and is used exclusively for remedying diseases of visceral organs such as heart and kidney.
The invention is directed to an agent for treating a skin ulcer. The agent can be a modified heparin, especially a low-molecular weight modified heparin. A typical agent in accordance with the present invention is a low-molecular weight modified heparin that has been substantially deprived of its anticoagulant activity, but retains its ability to bind to cell growth factors, cytokines and cell adhesion molecules.